Single chamber compact fuel processor

ABSTRACT

An apparatus for carrying out a multi-step process of converting hydrocarbon fuel to a substantially pure hydrogen gas feed includes a plurality of reaction zones arranged in a common reaction chamber. The multi-step process includes: providing a fuel to the fuel processor so that as the fuel reacts and forms the hydrogen rich gas, the intermediate gas products pass through each reaction zone as arranged in the reactor to produce the hydrogen rich gas.

Priority of U.S. Provisional Patent Application No. 60/286,684, filedApr. 26, 2001 is claimed under 35 U.S.C. §119.

BACKGROUND OF THE INVENTION

Fuel cells provide electricity from chemical oxidation-reductionreactions and possess significant advantages over other forms of powergeneration in terms of cleanliness and efficiency. Typically, fuel cellsemploy hydrogen as the fuel and oxygen as the oxidizing agent. The powergeneration is proportional to the consumption rate of the reactants.

A significant disadvantage that inhibits the wider use of fuel cells isthe lack of a widespread hydrogen infrastructure. Hydrogen has arelatively low volumetric energy density and is more difficult to storeand transport than the hydrocarbon fuels currently used in most powergeneration systems. One way to overcome this difficulty is the use ofreformers to convert the hydrocarbons to a hydrogen rich gas streamwhich can be used as a feed for fuel cells.

Hydrocarbon-based fuels, such as natural gas, LPG, gasoline, and diesel,require conversion processes to be used as fuel sources for most fuelcells. Current art uses multi-step processes combining an initialconversion process with several clean-up processes. The initial processis most often steam reforming (SR), autothermal reforming (ATR),catalytic partial oxidation (CPOX), or non-catalytic partial oxidation(POX). The cleanup processes usually include a combination ofdesulfurization, high temperature water-gas shift, low temperaturewater-gas shift, selective CO oxidation, or selective CO methanation.Alternative processes include hydrogen selective membrane reactors andfilters.

Despite the above work, there remains a need for a simple unit forconverting a hydrocarbon fuel to a hydrogen rich gas stream for use inconjunction with a fuel cell.

SUMMARY OF THE INVENTION

The present invention is generally directed to an apparatus forconverting hydrocarbon fuel into a hydrogen rich gas. In oneillustrative embodiment, the present invention includes a compact fuelprocessor for converting a hydrocarbon fuel feed into hydrogen rich gas,in which the fuel processor assembly includes a cylinder having a feedend and a manifold end, a removable manifold, and a plurality ofpredefined reaction zones within the cylinder, wherein each reactionzone is characterized by a chemical reaction that takes place within thereaction zone. The fuel processor also includes at least one coolingcoil having an inlet end and an outlet end connected to the manifoldend, wherein each of the at least one cooling coils is internallypositioned so as to remove heat from a particular reaction zone. Withinsuch an illustrative embodiment, the plurality of catalysts includesautothermal reforming catalyst, desulfurization catalyst, water gasshift catalyst, preferential oxidation catalyst, and combinations ofthese and similar catalysts. The hydrocarbon fuel feed utilized in theillustrative fuel processor is preheated, preferably by passing througha heat exchanger prior to being introduced to the cylinder oralternatively by a fuel pre-heater located in a function upstreamposition from the autothermal reforming reaction zone.

It is preferred in one illustrative embodiment that the cylinder isoriented substantially vertically with the manifold end of the cylinderbeing on top and the flow of reactants being generally upward from thefeed end to the manifold end. The present illustrative embodimentincludes a first reaction zone containing autothermal reformingcatalyst, a second reaction zone containing desulfurization catalyst, athird reaction zone containing water gas shift catalyst, and a fourthreaction zone containing preferential oxidation catalyst. Preferably,the first reaction zone is positioned at the feed end of the cylinder,the second reaction zone is positioned adjacent to the first reactionzone, the third reaction zone is positioned adjacent to the secondreaction zone, and the fourth reaction zone is positioned at themanifold end of the cylinder. A zone of ceramic beads may also bepositioned between the third reaction zone and the fourth reaction zonein order to improve the mixing of the hydrogen rich gas with air, whichis injected into the zone of ceramics beads through a fixed nozzle inthe manifold. This injection of air may be accomplished by well-knownmeans such as a simple gas injection tube or a porous tube. It should beappreciated by one of skill in the art that each reaction zone of theplurality of reaction zones may contain one or more catalysts.

It should be appreciated by one of skill in the art that each reactionzone of the plurality of reaction zones may contain one or morecatalysts. In one such illustrative embodiment, the catalysts areselected from autothermal reforming catalyst, desulfurization catalyst,water gas shift catalyst, preferential oxidation catalyst as well asmixtures and combinations of these and similar catalysts. Any particularreaction zone containing more than one catalyst may be separated from anadjacent reaction zone by a permeable plate that also serves to supportthe adjacent reaction zones. In one illustrative embodiment, the plateis selected from perforated metal, metal screen, metal mesh, sinteredmetal, porous ceramic, or combinations of these materials and similarmaterials. It is preferred within such an illustrative embodiment thatthe plate be at least partially composed of inconel, carbon steel,stainless steel, hatelloy, or other material suitable for thetemperature, pressure, and composition.

In a preferred aspect of the present invention, the compact fuelprocessor also includes a second cylinder having an anode tail gasoxidation catalyst bed for oxidizing the anode tail gas from a fuel cellto produce an exhaust gas. The second cylinder may have a pre-heatexchanger for heating the hydrocarbon fuel prior to feeding thehydrocarbon fuel to the first cylinder, and such a pre-heat exchangermay be positioned within the anode tail gas oxidation catalyst bed. Itis envisioned that the present illustrative embodiment also includes afifth reaction zone containing another preferential oxidation catalystbed. In such an embodiment, a second zone of ceramic beads, includingair injection nozzles as discussed above, may be positioned between thefourth reaction zone and the fifth reaction zone to ensure adequatemixing.

BRIEF DESCRIPTION OF THE DRAWINGS

The description is presented with reference to the accompanying drawingsin which:

FIG. 1 depicts a simple process flow diagram for one illustrativeembodiment of the present invention.

FIG. 2 depicts a first illustrative embodiment of a compact fuelprocessor apparatus of the present invention; and

FIG. 3 depicts a second illustrative embodiment of a compact fuelprocessor apparatus of the present invention.

FIG. 4 depicts a third illustrative embodiment of a compact fuelprocessor apparatus of the present invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention is generally directed to an apparatus forconverting hydrocarbon fuel into a hydrogen rich gas. In a preferredaspect, the apparatus and method described herein relate to a compactfuel processor for producing a hydrogen rich gas stream from ahydrocarbon fuel for use in fuel cells. However, other possible uses arecontemplated for the apparatus and method described herein, includingany use wherein a hydrogen rich stream is desired. Accordingly, whilethe invention is described herein as being used in conjunction with afuel cell, the scope of the invention is not limited to such use.

Each of the illustrative embodiments of the present invention describesa fuel processor or a process for using such a fuel processor with thehydrocarbon fuel feed being directed through the fuel processor. Thehydrocarbon fuel may be liquid or gas at ambient conditions as long asit can be vaporized. As used herein the term “hydrocarbon” includesorganic compounds having C—H bonds which are capable of producinghydrogen from a partial oxidation or steam reforming reaction. Thepresence of atoms other than carbon and hydrogen in the molecularstructure of the compound is not excluded. Thus, suitable fuels for usein the method and apparatus disclosed herein include, but are notlimited to hydrocarbon fuels such as natural gas, methane, ethane,propane, butane, naphtha, gasoline, and diesel fuel, and alcohols suchas methanol, ethanol, propanol, and the like.

The fuel processor feeds include hydrocarbon fuel, oxygen, and water.The oxygen can be in the form of air, enriched air, or substantiallypure oxygen. The water can be introduced as a liquid or vapor. Thecomposition percentages of the feed components are determined by thedesired operating conditions, as discussed below.

The fuel processor effluent stream from the present invention includeshydrogen and carbon dioxide and can also include some water, unconvertedhydrocarbons, carbon monoxide, impurities (e.g. hydrogen sulfide andammonia) and inert components (e.g., nitrogen and argon, especially ifair was a component of the feed stream).

FIG. 1 depicts a general process flow diagram illustrating the processsteps included in the illustrative embodiments of the present invention.One of skill in the art should appreciate that a certain amount ofprogressive order is needed in the flow of the reactants through thereactors disclosed herein.

Process step A is an autothermal reforming process in which tworeactions, partial oxidation (formula I, below) and optionally alsosteam reforming (formula II, below), are combined to convert the feedstream F into a synthesis gas containing hydrogen and carbon monoxide.Formulas I and II are exemplary reaction formulas wherein methane isconsidered as the hydrocarbon:CH₄+½O₂→2H₂+CO  (I)CH₄+H₂O→3 H₂+CO  (II)

The partial oxidation reaction occurs very quickly to the completeconversion of oxygen added and produces heat. The steam reformingreaction occurs slower and consumes heat. A higher concentration ofoxygen in the feed stream favors partial oxidation whereas a higherconcentration of water vapor favors steam reforming. Therefore, theratios of oxygen to hydrocarbon and water to hydrocarbon becomecharacterizing parameters. These ratios affect the operating temperatureand hydrogen yield.

The operating temperature of the autothermal reforming step can rangefrom about 550° C. to about 900° C., depending on the feed conditionsand the catalyst. The invention uses a catalyst bed of a partialoxidation catalyst with or without a steam reforming catalyst. Thecatalyst may be in any form including pellets, spheres, extrudate,monoliths, and the like. Partial oxidation catalysts should be wellknown to those with skill in the art and are often comprised of noblemetals such as platinum, palladium, rhodium, and/or ruthenium on analumina washcoat on a monolith, extrudate, pellet or other support.Non-noble metals such as nickel or cobalt have been used. Otherwashcoats such as titania, zirconia, silica, and magnesia have beencited in the literature. Many additional materials such as lanthanum,cerium, and potassium have been cited in the literature as “promoters”that improve the performance of the partial oxidation catalyst.

Steam reforming catalysts should be known to those with skill in the artand can include nickel with amounts of cobalt or a noble metal such asplatinum, palladium, rhodium, ruthenium, and/or iridium. The catalystcan be supported, for example, on magnesia, alumina, silica, zirconia,or magnesium aluminate, singly or in combination. Alternatively, thesteam reforming catalyst can include nickel, preferably supported onmagnesia, alumina, silica, zirconia, or magnesium aluminate, singly orin combination, promoted by an alkali metal such as potassium.

Process step B is a cooling step for cooling the synthesis gas streamfrom process step A to a temperature of from about 200° C. to about 600°C., preferably from about 300° C. to about 500° C., and more preferablyfrom about 375° C. to about 425° C., to optimize the temperature of thesynthesis gas effluent for the next step. This cooling may be achievedwith heat sinks, heat pipes or heat exchangers depending upon the designspecifications and the need to recover/recycle the heat content of thegas stream. One illustrative embodiment for step B is the use of a heatexchanger utilizing feed stream F as the coolant circulated through theheat exchanger. The heat exchanger can be of any suitable constructionknown to those with skill in the art including shell and tube, plate,spiral, etc. Alternatively, or in addition thereto, cooling step B maybe accomplished by injecting additional feed components such as fuel,air or water. Water is preferred because of its ability to absorb alarge amount of heat as it is vaporized to steam. The amounts of addedcomponents depend upon the degree of cooling desired and are readilydetermined by those with skill in the art.

Process step C is a purifying step. One of the main impurities of thehydrocarbon stream is typically sulfur, which is converted by theautothermal reforming step A to hydrogen sulfide. The processing coreused in process step C preferably includes zinc oxide and/or othermaterial capable of absorbing and converting hydrogen sulfide, and mayinclude a support (e.g., monolith, extrudate, pellet etc.).Desulfurization is accomplished by converting the hydrogen sulfide towater in accordance with the following reaction formula III:H₂S+ZnO→H₂O+ZnS  (III)

Other impurities such as chlorides can also be removed. The reaction ispreferably carried out at a temperature of from about 300° C. to about500° C., and more preferably from about 375° C. to about 425° C. Zincoxide is an effective hydrogen sulfide absorbent over a wide range oftemperatures from about 25° C. to about 700° C. and affords greatflexibility for optimizing the sequence of processing steps byappropriate selection of operating temperature.

The effluent stream may then be sent to a mixing step D in which wateris optionally added to the gas stream. The addition of water lowers thetemperature of the reactant stream as it vaporizes and supplies morewater for the water gas shift reaction of process step E (discussedbelow). The water vapor and other effluent stream components are mixedby being passed through a processing core of inert materials such asceramic beads or other similar materials that effectively mix and/orassist in the vaporization of the water. Alternatively, any additionalwater can be introduced with feed, and the mixing step can berepositioned to provide better mixing of the oxidant gas in the COoxidation step G disclosed below.

Process step E is a water gas shift reaction that converts carbonmonoxide to carbon dioxide in accordance with formula IV:H₂O+CO→H₂+CO₂  (IV)

This is an important step because carbon monoxide, in addition to beinghighly toxic to humans, is a poison to fuel cells. The concentration ofcarbon monoxide should preferably be lowered to a level that can betolerated by fuel cells, typically below 50 ppm. Generally, the watergas shift reaction can take place at temperatures of from 150° C. to600° C. depending on the catalyst used. Under such conditions, most ofthe carbon monoxide in the gas stream is converted in this step.

Low temperature shift catalysts operate at a range of from about 150° C.to about 300° C. and include for example, copper oxide, or coppersupported on other transition metal oxides such as zirconia, zincsupported on transition metal oxides or refractory supports such assilica, alumina, zirconia, etc., or a noble metal such as platinum,rhenium, palladium, rhodium or gold on a suitable support such assilica, alumina, zirconia, and the like.

High temperature shift catalysts are preferably operated at temperaturesranging from about 300° to about 600° C. and can include transitionmetal oxides such as ferric oxide or chromic oxide, and optionallyincluding a promoter such as copper or iron silicide. Also included, ashigh temperature shift catalysts are supported noble metals such assupported platinum, palladium and/or other platinum group members.

The processing core utilized to carry out this step can include a packedbed of high temperature or low temperature shift catalyst such asdescribed above, or a combination of both high temperature and lowtemperature shift catalysts. The process should be operated at anytemperature suitable for the water gas shift reaction, preferably at atemperature of from 150° C. to about 400° C. depending on the type ofcatalyst used. Optionally, a cooling element such as a cooling coil maybe disposed in the processing core of the shift reactor to lower thereaction temperature within the packed bed of catalyst. Lowertemperatures favor the conversion of carbon monoxide to carbon dioxide.Also, a purification processing step C can be performed between high andlow shift conversions by providing separate steps for high temperatureand low temperature shift with a desulfurization module between the highand low temperature shift steps.

Process step F′ is a cooling step performed in one embodiment by a heatexchanger. The heat exchanger can be of any suitable constructionincluding shell and tube, plate, spiral, etc. Alternatively a heat pipeor other form of heat sink may be utilized. The goal of the heatexchanger is to reduce the temperature of the gas stream to produce aneffluent having a temperature preferably in the range of from about 90°C. to about 150° C.

Oxygen is added to the process in step F′. The oxygen is consumed by thereactions of process step G described below. The oxygen can be in theform of air, enriched air, or substantially pure oxygen. The heatexchanger may by design provide mixing of the air with the hydrogen richgas. Alternatively, the embodiment of process step D may be used toperform the mixing.

Process step G is an oxidation step wherein almost all of the remainingcarbon monoxide in the effluent stream is converted to carbon dioxide.The processing is carried out in the presence of a catalyst for theoxidation of carbon monoxide and may be in any suitable form, such aspellets, spheres, monolith, etc. Oxidation catalysts for carbon monoxideare known and typically include noble metals (e.g., platinum, palladium)and/or transition metals (e.g., iron, chromium, manganese), and/orcompounds of noble or transition metals, particularly oxides. Apreferred oxidation catalyst is platinum on an alumina washcoat. Thewashcoat may be applied to a monolith, extrudate, pellet or othersupport. Additional materials such as cerium or lanthanum may be addedto improve performance. Many other formulations have been cited in theliterature with some practitioners claiming superior performance fromrhodium or alumina catalysts. Ruthenium, palladium, gold, and othermaterials have been cited in the literature as being active for thisuse.

Two reactions occur in process step G: the desired oxidation of carbonmonoxide (formula V) and the undesired oxidation of hydrogen (formulaVI) as follows:CO+½O₂→CO₂  (V)H₂+½O₂→H₂O  (VI)The preferential oxidation of carbon monoxide is favored by lowtemperatures. Since both reactions produce heat it may be advantageousto optionally include a cooling element such as a cooling coil disposedwithin the process. The operating temperature of process is preferablykept in the range of from about 90° C. to about 150° C. Process step Gpreferably reduces the carbon monoxide level to less than 50 ppm, whichis a suitable level for use in fuel cells, but one of skill in the artshould appreciate that the present invention can be adapted to produce ahydrogen rich product with higher and lower levels of carbon monoxide.

The effluent exiting the fuel processor is a hydrogen rich gas Pcontaining carbon dioxide and other constituents which may be presentsuch as water, inert components (e.g., nitrogen, argon), residualhydrocarbon, etc. Product gas may be used as the feed for a fuel cell orfor other applications where a hydrogen rich feed stream is desired.Optionally, product gas may be sent on to further processing, forexample, to remove the carbon dioxide, water or other components.

FIG. 2 depicts a cross-sectional view of a fuel processor 20 that is anillustrative embodiment of the present invention. One of ordinary skillin the art should see and appreciate that fuel or alternatively afuel/oxygen or alternatively a fuel/oxygen/water mixture F, isintroduced to the inlet of a heat exchanger 200. The preheated fuel F′leaves the heat exchanger 200 and is routed to the first reaction zone202. The first reaction zone 202 in the present illustrative embodimentis packed with a autothermal reforming reaction catalyst. Alternatively,this zone may be packed with a steam reforming catalyst. Such catalystmay be in pellet, sphere, or extrudate form; or supported on a monolith,reticulated foam, or any other catalyst support material. In someinstances a distribution plate (not shown) may be needed to achieve aneven distribution of fuel to the entire first reaction zone. Alsooptionally an electric pre-heater (not shown) may be utilized in thestart-up of the fuel processor. After the fuel has reacted in the firstreaction zone to form a hydrogen rich gas, the natural flow of the gasdue to pressure is for the hydrogen rich gas to flow into the secondreaction zone 204. In the present illustrative embodiment, the secondreaction zone is packed with a desulfurization catalyst, preferably zincoxide. Passage of the hydrogen rich gas over a desulfurization catalyst,such as zinc oxide, substantially reduces the concentration of sulfurcontaining compounds in the hydrogen rich gas stream. The desulfurizedhydrogen rich gas then passes into the third reaction zone 206. Thethird reaction zone of the present illustrative embodiment is packedwith a water-gas shift reactor catalyst or mixture of such catalyst asdiscussed above. The passage of the hydrogen rich gas over this catalystfurther enriches the hydrogen content and reduces the carbon monoxideconcentration. In some instances air or another suitable oxygen sourcemay now be injected into the fourth reaction zone so that thepreferential oxidation reaction is optimized. This may be accomplishedby well-known means such as a simple gas injection tube (not shown)inserted into the partial oxidation catalyst bed. In one preferredembodiment a porous tube is substantially incorporated into the designof the preferential oxidation reaction zone design and is designed suchthat an even distribution of injected oxygen is achieved. In theembodiment shown in this figure, the hydrogen rich gas is passed over azone of ceramic beads 208, which provides adequate mixing of thehydrogen rich gas with the air before entering the fourth reaction zone210. The hydrogen rich gas is then passed into the fourth reaction zone210 which contains a preferential oxidation catalyst. Such a catalystwill reduce the carbon monoxide concentration to preferably less than 50part per million as discussed above. The final product is a hydrogenrich gas H. It should also be noted that in one preferred andillustrative embodiment, an inert but porous and flexible material suchas glass wool, ceramic wool, rock wool, or other similar inert materialmay be used in the reaction zone transition regions 212. Such a materialserves to aid in the packing of the reactor with the various catalysts,assists in preventing inadvertent mixing of catalysts during transportand provides a cushioning or buffer zone between each of the differingreaction zones. Reaction temperature is controlled in the second, third,and fourth reaction zones by using cooling coils (218, 220, 222), whichcirculate coolant, such as water, air, hydrocarbon fuel feed, or anyrefrigerant, through the catalyst bed. In this illustrative embodiment,the inlet and outlet ends of each cooling coil are fixed in a manifold224 that is contained in the top cover for cylinder 226, which enclosesthe various reaction zones. One of skill in the art should appreciatethat a number of factors affect the heat transfer process including theflow rate of fuel, the number of coils present in any particularreaction zone, the diameter of the tubing used to make the coils, thepresence or absence of fins on the coils and so forth. However, suchheat transfer considerations can be optimized through routinecalculations and experimentation. In this embodiment, air A is alsoinjected into the zone of ceramic beads through a nozzle fixed inmanifold 224. Hydrogen rich gas H is also withdrawn through manifold224.

FIG. 2 also shows the optional embodiment of adding an additional heatexchanger 214 and preferential oxidation catalyst bed 216. The purposefor heat exchanger 214 is primarily to cool the hydrogen rich gas H. Theamount of cooling may or may not result in condensing water W out of thegas, for further oxidation in bed 216, which ensures achieving a carbonmonoxide concentration of less that 50 part per million in hydrogen richgas H′ The hydrogen rich gas H or H′ is preferably used in a fuel cellor may be stored or used in other processes that should be apparent toone of skill in the art. Another preferred embodiment of the presentinvention includes an anode tail gas oxidizer, which oxidizes the anodetail gas T from a fuel cell (not shown). This addition is a useful heatsource for preheating hydrocarbon fuel F in heat exchanger 200.

One of skill in the art after reviewing the above description of FIG. 2should understand and appreciate that each module performs a separateoperational function. Feed stream F (200) is introduced through inletpipe (not shown) and product gas P 216 is drawn off via outlet pipe (notshown). Reaction zone 208 is the autothermal reforming reaction zonecorresponding to process step A of FIG. 1. An electric heater (notshown) may be installed at the bottom inlet of the reactor for start-upheat. Reaction zone 210 is purifying reaction zone corresponding toprocess step C of FIG. 1. Reaction zone 212 is water gas shift reactionzone corresponding to process step E of FIG. 1. The cooling stepcorresponding to process step F′ of FIG. 1 is carried out by a heatexchanger 202. Reaction zone 214 is an oxidation step corresponding toprocess step G of FIG. 1. Air source (not shown) provides a source foroxygen to process gas for the oxidation reaction (Equation V) ofreaction zone 214. Reaction zone 214 also contains a heat exchanger 202positioned within or surrounding the catalyst bed so as to maintain adesired oxidation reaction temperature. One of skill in the art shouldappreciate that the process configuration described in this embodimentmay vary depending on numerous factors, including but not limited tofeedstock quality and required product quality.

FIG. 3 depicts a cross-sectional view of a fuel processor 30 that isanother illustrative embodiment of the present invention. One ofordinary skill in the art should see and appreciate that fuel oralternatively a fuel/oxygen or alternatively a fuel/oxygen/water mixtureF, is introduced to the inlet of a container 300, which contains ananode tail gas oxidizer catalyst bed, which oxidizes the anode tail gasT from a fuel cell (not shown). Container 300 also contains a heatexchanger which provides a useful preheating of hydrocarbon fuel F. Thepreheated fuel F′ leaves container 300 and is routed to the firstreaction zone 302. The first reaction zone 302 in the presentillustrative embodiment is packed with a autothermal reforming reactioncatalyst. Such catalyst may be in pellet, sphere, or extrudate form; orsupported on a monolith, reticulated foam, or any other catalyst supportmaterial. In some instances a distribution plate (not shown) may beneeded to achieve an even distribution of fuel to the entire firstreaction zone. Also optionally an electric pre-heater (not shown) may beutilized in the start-up of the fuel processor. After the fuel hasreacted in the first reaction zone to form a hydrogen rich gas, thenatural flow of the gas due to pressure is for the hydrogen rich gas toflow into the second reaction zone 304. In the present illustrativeembodiment, the second reaction zone is packed with a desulfurizationcatalyst, preferably zinc oxide. Passage of the hydrogen rich gas over adesulfurization catalyst, such as zinc oxide, substantially reduces theconcentration of sulfur containing compounds in the hydrogen rich gasstream. The desulfurized hydrogen rich gas is then passes into the thirdreaction zone 306. The third reaction zone of the present illustrativeembodiment is packed with a water-gas shift reactor catalyst or mixtureof such catalyst as discussed above. The passage of the hydrogen richgas over this catalyst further enriches the hydrogen content and reducesthe carbon monoxide concentration. In some instances air or anothersuitable oxygen source may now be injected into the fourth reaction zoneso that the preferential oxidation reaction is optimized. This may beaccomplished by well-known means such as a simple gas injection tube(not shown) inserted into the partial oxidation catalyst bed. In onepreferred embodiment a porous tube is substantially incorporated intothe design of the preferential oxidation reaction zone design and isdesigned such that an even distribution of injected oxygen is achieved.In the embodiment shown in this figure, the hydrogen rich gas is passedover a zone of ceramic beads 308, which provides adequate mixing of thehydrogen rich gas with the air before entering the fourth reaction zone310. The hydrogen rich gas is then passed into the fourth reaction zone310 which contains a preferential oxidation catalyst. Such a catalystwill reduce the carbon monoxide concentration to preferably less that 50part per million as discussed above. Optionally, an additional layer ofceramic beads and a fifth reaction zone (not shown) containing apreferential oxidation catalyst can be employed to ensure that thecarbon monoxide concentration is reduced to preferably less than 50parts per million. The final product is a hydrogen rich gas H. It shouldalso be noted that in one preferred and illustrative embodiment, aninert but porous and flexible material such as glass wool, ceramic wool,rock wool, or other similar inert material may be used in the reactionzone transition regions 312. Such a material serves to aid in thepacking of the reactor with the various catalysts, assists in preventinginadvertent mixing of catalysts during transport and provides acushioning or buffer zone between each of the differing reaction zones.Reaction temperature is controlled in the second, third, and fourthreaction zones by using cooling coils (318, 320, 322), which circulatecoolant, such as water, air, hydrocarbon fuel feed, or any refrigerant,through the catalyst bed. In this illustrative embodiment, the inlet andoutlet ends of each cooling coil are fixed in a manifold 324 that iscontained in the top cover for cylinder 326, which encloses the variousreaction zones. One of skill in the art should appreciate that a numberof factors affect the heat transfer process including the flow rate offuel, the number of coils present in any particular reaction zone, thediameter of the tubing used to make the coils, the presence or absenceof fins on the coils and so forth. However, such heat transferconsiderations can be optimized through routine calculations andexperimentation. In this embodiment, air A is also injected into thezone of ceramic beads through a nozzle fixed in manifold 324. Hydrogenrich gas H is also withdrawn through manifold 324.

One of skill in the art after reviewing the above description of FIG. 3should understand and appreciate that each reaction zone performs aseparate operational function. Reaction zone 302 is the autothermalreforming reaction zone corresponding to process step A of FIG. 1. Anelectric heater (not shown) may be installed at the bottom inlet of thereactor for start-up heat. Reaction zone 304 is a purifying reactionzone corresponding to process step C of FIG. 1. Reaction zone 306 is awater gas shift reaction zone corresponding to process step E of FIG. 1.The cooling step corresponding to process step F′ of FIG. 1 is carriedout by cooling coil 320. Reaction zone 310 is an oxidation stepcorresponding to process step G of FIG. 1. Air source (not shown)provides a source for oxygen to process gas for the oxidation reaction(Equation V) of reaction zone 310. Reaction zone 310 also containscooling coil 322 positioned within or surrounding the catalyst bed so asto maintain a desired oxidation reaction temperature. One of skill inthe art should appreciate that the process configuration described inthis embodiment may vary depending on numerous factors, including butnot limited to feedstock quality and required product quality.

FIG. 4 depicts a cross-sectional view of a fuel processor 40 that is yetanother illustrative embodiment of the present invention. One ofordinary skill in the art should see and appreciate that fuel oralternatively a fuel/oxygen or alternatively a fuel/oxygen/water mixtureF, is introduced to the inlet of a heat exchanger 400. The preheatedfuel F′ leaves the heat exchanger 400 and is routed to the firstreaction zone 402. The first reaction zone 402 in the presentillustrative embodiment is packed with a autothermal reforming catalystor steam reforming catalyst. Such catalyst may be in pellet, sphere, orextrudate form; or supported on a monolith, reticulated foam, or anyother catalyst support material. In some instances a distribution plate(not shown) may be needed to achieve an even distribution of fuel to theentire first reaction zone. Also optionally an electric pre-heater (notshown) may be utilized in the start-up of the fuel processor. After thefuel has reacted in the first reaction zone to form a hydrogen rich gas,the natural flow of the gas due to pressure is for the hydrogen rich gasto flow into the second reaction zone 404. In the present illustrativeembodiment, the second reaction zone is packed with a desulfurizationcatalyst, preferably zinc oxide. Passage of the hydrogen rich gas over adesulfurization catalyst, such as zinc oxide, substantially reduces theconcentration of sulfur containing compounds in the hydrogen rich gasstream. The desulfurized hydrogen rich gas is then passes into the thirdreaction zone 406. The third reaction zone of the present illustrativeembodiment is packed with a water-gas shift reactor catalyst or mixtureof such catalyst as discussed above. The passage of the hydrogen richgas over this catalyst further enriches the hydrogen content and reducesthe carbon monoxide concentration. In some instances air or anothersuitable oxygen source may now be injected into the fourth reaction zoneso that the preferential oxidation reaction is optimized. This may beaccomplished by well-known means such as a simple gas injection tube(not shown) inserted into the partial oxidation catalyst bed. In onepreferred embodiment a porous tube is substantially incorporated intothe design of the preferential oxidation reaction zone design and isdesigned such that an even distribution of injected oxygen is achieved.In the embodiment shown in this figure, the hydrogen rich gas is passedover a zone of ceramic beads 408, which provides adequate mixing of thehydrogen rich gas with the air before entering the fourth reaction zone410. The hydrogen rich gas is then passed into the fourth reaction zone410 which contains a preferential oxidation catalyst. Such a catalystwill reduce the carbon monoxide concentration to preferably less than 50parts per million as discussed above. The final product is a hydrogenrich gas H. It should also be noted that in one preferred andillustrative embodiment, an inert but porous and flexible material suchas glass wool, ceramic wool, rock wool, or other similar inert materialmay be used in the reaction zone transition regions 412. Such a materialserves to aid in the packing of the reactor with the various catalysts,assists in preventing inadvertent mixing of catalysts during transportand provides a cushioning or buffer zone between each of the differingreaction zones. Reaction temperature is controlled in the second, third,and fourth reaction zones by directly injecting water into the catalystbeds. In this illustrative embodiment, the inlet nozzle for eachinjection line is fixed in a manifold 424 that is contained in the topcover for cylinder 426, which encloses the various reaction zones. Oneof skill in the art should appreciate that a number of factors affectthe controllability of the reaction temperatures, including the size ofthe nozzles, the flow rate of fuel, and the number and location of thenozzles in each catalyst bed. However, such heat transfer considerationscan be optimized through routine calculations and experimentation. Inthis embodiment, air A is also injected into the zone of ceramic beadsthrough a nozzle fixed in manifold 424. Hydrogen rich gas H is alsowithdrawn through manifold 424.

FIG. 4 also shows the optional embodiment of adding an additional heatexchanger 414 and preferential oxidation catalyst bed 416. The purposefor heat exchanger 414 is primarily to cool the hydrogen rich gas H,thereby condensing water W out of the gas, for further oxidation in bed416, which ensures achieving a carbon monoxide concentration of lessthan 50 parts per million in hydrogen rich gas H′ The hydrogen rich gasH or H′ is preferably used in a fuel cell or may be stored or used inother processes that should be apparent to one of skill in the art.Another preferred embodiment of the present invention is anode tail gasoxidizer, which oxidizes the anode tail gas T from a fuel cell (notshown). This addition is a useful heat source for preheating hydrocarbonfuel F in heat exchanger 400.

One of skill in the art after reviewing the above description of FIG. 4should understand and appreciate that each reaction zone performs aseparate operational function. Reaction zone 402 is the autothermalreforming reaction zone corresponding to process step A of FIG. 1. Anelectric heater (not shown) may be installed at the bottom inlet of thereactor for start-up heat. Reaction zone 404 is a purifying reactionzone corresponding to process step C of FIG. 1. Reaction zone 406 is awater gas shift reaction zone corresponding to process step E of FIG. 1.The cooling step corresponding to process step F′ of FIG. 1 is carriedout by the direct water injection into reaction zone 406. Reaction zone410 is an oxidation step corresponding to process step G of FIG. 1. Airsource (not shown) provides a source for oxygen to process gas for theoxidation reaction (Equation V) of reaction zone 410. Reaction zone 410also contains direct water injection to maintain a desired oxidationreaction temperature. One of skill in the art should appreciate that theprocess configuration described in this embodiment may vary depending onnumerous factors, including but not limited to feedstock quality andrequired product quality.

In view of the above disclosure, one of ordinary skill in the art shouldunderstand and appreciate that the present invention includes manypossible illustrative embodiments that depend upon design criteria. Onesuch illustrative embodiment includes a compact fuel processor forconverting a hydrocarbon fuel feed into hydrogen rich gas, in which thefuel processor assembly includes a cylinder having a feed end and amanifold end, a removable manifold, and a plurality of predefinedreaction zones within the cylinder, wherein each reaction zone ischaracterized by a chemical reaction that takes place within thereaction zone. The fuel processor also includes at least one coolingcoil having an inlet end and an outlet end connected to the manifoldend, wherein each of the at least one cooling coils is internallypositioned so as to remove heat from a particular reaction zone ordirect injection of water to control the temperature in a particularreaction zone. Within such an illustrative embodiment, the plurality ofcatalysts includes autothermal reforming catalyst or steam reformingcatalyst, desulfurization catalyst, water gas shift catalyst,preferential oxidation catalyst, and mixtures and combinations of theseand similar catalysts. The hydrocarbon fuel feed utilized in theillustrative fuel processor is preheated, preferably by passing througha heat exchanger prior to being introduced to the cylinder oralternatively by a fuel pre-heater located in a function upstreamposition from the autothermal reforming reaction zone. A wide variety ofhydrocarbon fuels may be utilized. However, in one illustrativeembodiment the hydrocarbon fuel is selected form natural gas, gasoline,diesel, fuel oil, propane, liquefied petroleum, methanol, ethanol orother similar and suitable hydrocarbons and mixtures of these. It ispreferred in one illustrative embodiment that the cylinder is orientedsubstantially vertically with the manifold end of the cylinder being ontop and the flow of reactants being generally upward from the feed endto the manifold end. The present illustrative embodiment comprises afirst reaction zone containing autothermal reforming catalyst, a secondreaction zone containing desulfurization catalyst, a third reaction zonecontaining water gas shift catalyst, and a fourth reaction zonecontaining preferential oxidation catalyst. Preferably, the firstreaction zone is positioned at the feed end of the cylinder, the secondreaction zone is positioned adjacent to the first reaction zone, thethird reaction zone is positioned adjacent to the second reaction zone,and the fourth reaction zone is positioned at the manifold end of thecylinder. A zone of ceramic beads may also be positioned between thethird reaction zone and the fourth reaction zone in order to improve themixing of the hydrogen rich gas with air, which is injected into thezone of ceramics beads through a fixed nozzle in the manifold. Thisinjection of air may be accomplished by well-known means such as asimple gas injection tube or a porous tube. It should be appreciated byone of skill in the art that each reaction zone of the plurality ofreaction zones may contain one or more catalysts. In one suchillustrative embodiment, the catalysts are selected from autothermalreforming catalyst, desulfurization catalyst, water gas shift catalyst,preferential oxidation catalyst as well as mixtures and combinations ofthese and similar catalysts. Any particular reaction zone containingmore than one catalyst may be separated from an adjacent reaction zoneby a permeable plate that also serves to support the adjacent reactionzones. In one illustrative embodiment, the plate is selected fromperforated metal, metal screen, metal mesh, sintered metal, porousceramic, or combinations of these materials and similar materials. It ispreferred within such an illustrative embodiment that the plate be atleast partially composed of inconel, carbon steel, stainless steel,hatelloy, or other material suitable for the temperature, pressure, andcomposition. In a preferred aspect of the present invention, the compactfuel processor also comprises a second cylinder having an anode tail gasoxidation catalyst bed for oxidizing the anode tail gas from a fuel cellto produce an exhaust gas. The second cylinder may have a pre-heatexchanger for heating the hydrocarbon fuel prior to feeding thehydrocarbon fuel to the first cylinder, and such a pre-heat exchangermay be positioned within the anode tail gas oxidation catalyst bed. Itis envisioned that the present illustrative embodiment also includes afifth reaction zone containing another preferential oxidation catalystbed. In such an embodiment, a second zone of ceramic beads, includingair injection nozzles as discussed above, may be positioned between thefourth reaction zone and the fifth reaction zone to ensure adequatemixing.

Another such illustrative embodiment includes a compact fuel processorfor converting a hydrocarbon fuel feed into hydrogen rich gas, in whichthe fuel processor assembly includes a cylinder having a feed end and amanifold end, a removable manifold, and a plurality of predefinedreaction zones within the cylinder, wherein each reaction zone ischaracterized by a chemical reaction that takes place within thereaction zone. Instead of cooling coils or other heat exchangers,temperature control in each reaction zone is controlled through directwater injection. It is preferred in one illustrative embodiment that thecylinder is oriented substantially vertically with the manifold thecylinder being on top and the flow of reactants being generally upwardfrom the feed end to the manifold end. The present illustrativeembodiment comprises a first reaction zone containing autothermalreforming catalyst, a second reaction zone containing desulfurizationcatalyst, a third reaction zone containing water gas shift catalyst, anda fourth reaction zone containing preferential oxidation catalyst.Preferably, the first reaction zone is positioned at the feed end of thecylinder, the second reaction zone is positioned adjacent to the firstreaction zone, the third reaction zone is positioned adjacent to thesecond reaction zone, and the fourth reaction zone is positioned at themanifold end of the cylinder. A zone of ceramic beads may also bepositioned between the third reaction zone and the fourth reaction zonein order to improve the mixing of the hydrogen rich gas with air, whichis injected into the zone of ceramics beads through a fixed nozzle inthe manifold. This injection of air may be accomplished by well-knownmeans such as a simple gas injection tube or a porous tube. It should beappreciated by one of skill in the art that each reaction zone of theplurality of reaction zones may contain one or more catalysts. In onesuch illustrative embodiment, the catalysts are selected fromautothermal reforming catalyst or steam reforming catalyst,desulfurization catalyst, water gas shift catalyst, preferentialoxidation catalyst as well as mixtures and combinations of these andsimilar catalysts. Any particular reaction zone containing more than onecatalyst may be separated from an adjacent reaction zone by a permeableplate that also serves to support the adjacent reaction zones. In oneillustrative embodiment, the plate is selected from perforated metal,metal screen, metal mesh, sintered metal, porous ceramic, orcombinations of these materials and similar materials. It is preferredwithin such an illustrative embodiment that the plate be at leastpartially composed of INCONEL® (a trademark registered for use inassociation with nickel alloys and alloys of nickel, chromium and iron),carbon steel, stainless steel.

While the apparatus, compositions and methods of this invention havebeen described in terms of preferred or illustrative embodiments, itwill be apparent to those of skill in the art that variations may beapplied to the process described herein without departing from theconcept and scope of the invention. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the scope and concept of the invention as it is set out in thefollowing claims.

1. A compact fuel processor for converting a hydrocarbon fuel feed tohydrogen rich gas, comprising: a cylinder having a feed end and amanifold end, wherein the cylinder has a removable manifold; a pluralityof predefined reaction zones within the cylinder, wherein each reactionzone is characterized by a chemical reaction that takes place within thereaction zone; and at least one cooling coil having an inlet end and anoutlet end connected to the manifold end, wherein each of the at leastone cooling coils is internally positioned so as to remove heat from aparticular reaction zone.
 2. The compact fuel processor of claim 1,wherein the cylinder is oriented substantially vertically with themanifold end of the cylinder being on top.
 3. The compact fuel processorof claim 1, wherein a first reaction zone contains autothermal reformingcatalyst or steam reforming catalyst, a second reaction zone containsdesulfurization catalyst, a third reaction zone contains water gas shiftcatalyst, and a fourth reaction zone contains preferential oxidationcatalyst.
 4. The compact fuel processor of claim 3, wherein the firstreaction zone is positioned at the feed end of the cylinder, the secondreaction zone is positioned adjacent to the first reaction zone, thethird reaction zone is positioned adjacent to the second reaction zone,and the fourth reaction zone is positioned at the manifold end of thecylinder.
 5. The compact fuel processor of claim 4, wherein a zone ofceramic beads is positioned between the third reaction zone and thefourth reaction zone.
 6. The compact fuel processor of claim 5, furthercomprising an air injection means for injecting air into the zone ofceramic beads, wherein the air injection means is connected to themanifold.
 7. The compact fuel processor of claim 4, wherein a reactionzone containing more than one catalyst is separated from an adjacentreaction zone by a permeable plate.
 8. The compact fuel processor ofclaim 7, wherein the permeable plate is perforated metal, metal screen,metal mesh, sintered metal, or porous ceramic.
 9. The compact fuelprocessor of claim 8, wherein the permeable plate is of a materialselected from the group consisting of inconel, carbon steel, stainlesssteel, hastelloy, and other material suitable for the temperature,pressure, and composition.
 10. The compact fuel processor of claim 1,further comprising a second cylinder comprising a anode tail gasoxidation catalyst bed for oxidizing the anode tail gas from a fuel cellto produce an exhaust gas.
 11. The compact fuel processor of claim 10,wherein the second cylinder further comprises a pre-heat exchanger forheating the hydrocarbon fuel prior to feeding the hydrocarbon fuel tothe first cylinder.
 12. The compact fuel processor of claim 11, whereinthe pre-heat exchanger is positioned within the anode tail gas oxidationcatalyst bed.
 13. The compact fuel processor of claim 3, wherein a fifthreaction zone contains preferential oxidation catalyst.
 14. The compactfuel processor of claim 13, wherein the first reaction zone ispositioned at the feed end of the cylinder, the second reaction zone ispositioned adjacent to the first reaction zone, the third reaction zoneis positioned adjacent to the second reaction zone, the fourth reactionzone is positioned adjacent to the third reaction zone, and the fifthreaction zone is positioned at the manifold end of the cylinder.
 15. Thecompact fuel processor of claim 14, further comprising a first zone ofceramic beads positioned between the third reaction zone and the fourthreaction zone, and a second zone of ceramic beads positioned between thefourth reaction zone and the fifth reaction zone.
 16. The compact fuelprocessor of claim 15, further comprising air injection means forinjecting air into each zone of ceramic beads, wherein the air injectionmeans is connected to the manifold.
 17. A compact fuel processor forconverting a hydrocarbon fuel feed to hydrogen rich gas, comprising: acylinder having a feed end and a manifold end, wherein the cylinder hasa removable manifold; a plurality of predefined reaction zones withinthe cylinder, wherein each reaction zone is characterized by a chemicalreaction that takes place within the reaction zone; and at least oneinjection means for injecting water into a particular reaction zone,wherein each injection means is connected to the manifold.
 18. Thecompact fuel processor of claim 17, wherein the cylinder is orientedsubstantially vertically with the manifold end of the cylinder being ontop.
 19. The compact fuel processor of claim 17, wherein a firstreaction zone contains autothermal reforming catalyst or steam reformingcatalyst, a second reaction zone contains desulfurization catalyst, athird reaction zone contains water gas shift catalyst, and a fourthreaction zone contains preferential oxidation catalyst.
 20. The compactfuel processor of claim 19, wherein the first reaction zone ispositioned at the feed end of the cylinder, the second reaction zone ispositioned adjacent to the first reaction zone, the third reaction zoneis positioned adjacent to the second reaction zone, and the fourthreaction zone is positioned at the manifold end of the cylinder.
 21. Thecompact fuel processor of claim 20, wherein a zone of ceramic beads ispositioned between the third reaction zone and the fourth reaction zone.22. The compact fuel processor of claim 21, further comprising an airinjection means for injecting air into the zone of ceramic beads,wherein the air injection means is connected to the manifold.
 23. Thecompact fuel processor of claim 19, wherein a reaction zone is separatedfrom an adjacent reaction zone by a permeable plate.
 24. The compactfuel processor of claim 23, wherein the permeable plate is perforatedmetal, metal screen, metal mesh, sintered metal, or porous ceramic. 25.The compact fuel processor of claim 24, wherein the permeable plate isof a material selected from the group consisting of inconel, carbonsteel, stainless steel, hastelloy, and other material suitable for thetemperature, pressure, and composition.